This is a great site for 411 on shortage of meds:
https://www.ashp.org/drug-shortages/current-shortages/drug-shortage-detail.aspx?id=961
I ran the key ingredient of Vyvanse for you there. As you can see, most of the manufacturers are out of stock. I reached out to the manufacturers of Dex and had them send me the pharmas they stock. They can't tell you ETA of stock there as they sell direct via wholesaler but you can at least know where the manufacturers who have stock are selling to. Keep calling those pharmas to check in to see if they have.
The other thing if you're not aware is that the ADHD meds shortage in large part is due to the controlled substance it is and being on the same list as opioids which is why so many manufacturers can't process - there's a specific volume set by government for making and delivering these meds. There's countless articles and PBS recently did a story about this. It's so many ADHD meds and COVID made it so that everyone has been diagnosed with ADHD so you have different subs for meds making it that much harder to find your Rx.